Leading-in insulator



Oct. 29, 1940.

B. BERGHAUS ET AL LITADINtz-Ill INSULATOR Filed March 28; 1938 s 5 a a z a #62 w 5% g s fihm f p f m r n v I e 5W Y 6 5 Hmw u 3 4. K J r m b a q B w a M flaw m wmflhfihhfln M 7 j w a M a M a 0 H 8 w @w E 5 6 I a O 8 7 8 1 Patented Oct. 29, 1940 PATENT OFFICE LEADING-IN INSULATOR Bernhard Berghaus,

Berlin-Lankwitz, Wilhelm Burkhardt, Berlin-Grunewald, and ltudoll.

Reinecke,

Berlin-Lankwitz, Germany;

said

Burkhardt and said Reinecke assignors to said Berghaus Application March 28, 1938, Serial No. 198,556 In Germany March 25, 1937 I 9 Claims.

This invention relates to a cathode disintegration apparatus and more particularly to the leadin to which the cathode to be disintegrated is connected. Cathode disintegration apparatus 5 comprises a vacuum chamber in which objects are metallised by cathode disintegration, the cathode material to be disintegrated being connected to the negative pole of a source of high voltage and being introduced into the said vac- 10 uum chamber by means of a lead-in which is insulated and vacuum-tight.

It is known from numerous publications on cathode disintegration that the insulation and screening of the lead-in, and more particularly 15 of the lead-in of the cathode, cause difliculties. If voltages higher than 3000 volts are employed in order to obtain greater current density, the insulation is damaged after 'a short time, and the discharge starts mainly at the voltage lead- 29 in, whereby disturbing gases are freed which discolour the metal deposit that is obtained, and render it useless. The object of the present invention is to overcome thesedrawbacks.

The invention pertains to an insulated lead-in 25 for cathode disintegration apparatus in which the insulating material and the sealing material of the conductor are so arranged that they are not reached by the charge carriers and the metal vapour in the vacuum chamber in which the ob- 30 jects are metallised by cathode disintegration. For this purpose, the conductor is provided with a metal screen, preferably projecting into' the vacuum disintegration chamber. The distance between the conductor and the metal screen is 35 made smaller than the distance at which a glow discharge would be caused around the lead-in conductor. The distance of the metal screen from the current lead varies according to the nature, pressure and temperature of the gas, between 0.1 to 20 and preferably 0.5 to 5- millimeters and the metal screen has such a length that the glow and the charge carriers from the ionised atmosphere and metal vapour do not come into contact with the insulating and the sealing ma- 5 terial. The metal screen takes up a positive potential in the ionised gas space. electric contact with the casing of the cathode disintegration chamber and may also be earthed. The metal screen of the electric lead-in may, in

addition to being insulated from the conductor, be preferably also insulated with respect to the casing, and carry another voltage.

The insulation and the sealing of the conductor are preferably arranged outside the cathode 55 disintegration apparatus so that they are acces- It may be in sible from the outside. The conductor may be constructed as a circular hollow member, the inner wall of which may be cooled by a cooling medium, such asair, oil, or water. The screening sleeve may be provided'at its end with a cap having a hole through which the conductor passes so as to protect the insulation with respect to the deposit of metal splinters which may be released from the electrodes. The insulation with respect to the vacuum disintegration chamber is preferably provided between the electric lead-in, which is formed with a flange, and the outer wall of the vacuum vessel. The insulation may at the same timeform the seal when it consists of an elastic material capable of being deformed. The insulation may consist of glass, quartz, porcelain, amber, mica, artificial resin and the like, and be made air-tight on the abutting surfaces by rubber discs or by metal discs of lead, copper, aluminium, or such metals which are easily deformed by pressure.

Also the wall of the chamber may be provided with a cooling device in the proximity of the sealing and insulation. Also the metal screen of the conductor may be made hollow so as to be capable of being cooled. The cooling has the advantage that it condenses the metal dust, which is formed and which is mostly neutral and, therefore, not capable of following an electric field, on the cooled screen or electric lead-in before it can reach the insulator.

In addition to-the great reliability of operation in the case of large outputs and high temperatures at the cathodes to be distintegrated, the screening prevents all those parts which carry current but do not consist of the material to be disintegrated from being disintegrated.

According to a modification the conductor is surrounded by a plurality of concentric metal screens which are insulated relatively to one an- 40 other and to the conductor, and are arranged at a short distance from one another. The metal screens may preferably carry different voltages with respect to one another and the conductor.

.For the regulation of the voltage distribution on the metal screens, condensers or resistances, or condensers and resistances used jointly are preferably provided.

Various modes of carrying the invention into effect are illustrated diagrammatically, and by way of example in the accompanying drawing, in e which Figure 1 is a vertical section through apparatus for cathode disintegration embodying a form of construction of insulated lead-in conductor;

. voltage may be applied to the metal tube 84.

Figure 2 is a vertical sectional view-of a further form of construction in which the metal screen is cooled; and

Figure 3 is a vertical section through another form of construction in which a plurality of concentric metal screens surrounding the lead-in conductors are used.

Referring to Figure 1, 2 is the bottom of the cathode disintegration chamber which carries in a gas-tight manner a removable upper part 68. The anode 69 and the cathode 10 are fed from a source of disintegration voltage (not shown). II is the article to be coated. 12 is the member supporting the cathode 10, which may be of any shape or size. The supporting member 12 is introduced in an insulating manner through a hole in the bottom plate into .the disintegration chamber, for instance, by means of an insulating plate 13. which may consist of rubber, and be secured by screws I4 through the intermediary of metal rings and I6 and insulating members 11 and 78. The supporting member .12 is, for instance, made hollow, and is provided with an inlet pipe 19 and an outlet pipe 83 for a cooling medium. 8| is the electric lead to the cathode. The bottom plate is provided with a short connecting pipe 82 for the vacuum pump and with a pipe 83 for the supply of gas.

According to thu invention, at a short distance from the supporting member 12 there is provided a metal screen, for instance a metal tube 84, which carries at the free end a removable perforated metal cap 85. The metal screen or the metal tube 84 is secured in the bottom plate by means of an insulating member 86. However, the latter member may be dispensed with, in which case the metal tube 84 is secured directly in the bottom plate, which may be of metal. A positive Also the base plate carrying the metal tube 84, or the disintegration vessel may be connected to the positive voltage.-

The characteristic of the electric lead-in according to Fig. 2 is that the metal screen 3| is made hollow and capable of being cooled, the cooling medium being supplied by the pipe 32 and is led out through the pipe 33. 34 is the insulating member, 35 the press ring of insulating material and 35 a sealing ring.

Referring to Figure 3, 2 is the wall of the vacuum chamber I, which wall is of metal, into which vacuum chamber the conductor 3 is introduced through a hole, the conductor being, for instance, made hollow and being cooled by a cooling medium, such as water, oil or air. The cooling medium is introduced through the pipe 4 and is led out through the pipe 5. The conductor 3 is surrounded by a plurality of, for instance four, cylindrical metal screens 6a, 6b, 6c and 6d, which are provided at one end with a flange, and at the other end project into the disintegration chamber to such an extent that no discharges or metal particles can reach the insulations and sealings provided outside the vacuum chamber through the narrow annular spaces between the conductor 3 and the screen 6a,and between the other screens. The insulation is efiected by means of rings 1a, lb, To and 1d. The flange I0 of the conductor 3 is firmly clamped by the ring ll of insulating material and screws l2. I4 is a lead connected to the conductor 3. 59, 60, 6| and 62 are resistances and 63, 64, 65 and 66 are condensers for the regulation of the voltage on the screens. Voltages up to 10.000 volts can be applied to the described lead-in conductor hereinbefore described without 1. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated metal housing providing a chamber for receiving articles to be coated, an anode supported within said housing and insulated therefrom, said housing having a hole' therein, a cathode, an elongated metal member of smaller cross-sectional area than said hole extending into said chamber through said hole connected to and supporting the cathode at the inner end thereof, a flange carried by the outer end of said member spaced from said housing, a tubular shaped metal screen sealed with respect to said housing extending through said hole and surrounding said member to provide an elongated annular space therebetween, and insulating means interposed between and engaged by the outer end of said tubular shaped screen and said flange.

2. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated metal housing providing a chamber for receiving articles to be coated, an anode supported within said housing and insulated there- 'from, said housing having a hole therein, a cathode, an elongated metal member of smaller crosssectional area than said hole extending into said chamber through said hole connected to and supporting the cathode at the inner end thereof, a flange carried by the outer end of said member spaced from said housing, a tubuiarshaped metal screen extending through said hole and surrounding said member to provide an elongated annular space therebetween, insulating means interposed between and engaged by the outer end of said tubular shaped screen and said flange, and means interposed between the tubular screen and said housing providing a sealed connection therebetween.

8. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated housing providing a chamber for receiving articles to be coated, an anode supported within the housing and insulated therefrom, a cathode, said housing having a hole therein, an elongated metal member extending into said chamber through said hole connected to and supporting said cathode at the inner end thereof, a metal screen sealed with respect to said housing surrounding said elongated member so as to provide a relatively long narrow space between the screen and said member extending from the housing to the inner end of said member, and insulating means arranged entirely outside said housing between and engaged by said member and said screen.

4. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated metal housing providing a chamber for receiving articles to be coated, an anode supported within said housing and insulated therefrom, said housing having a hole therein, a. cathode, a closed end elongated hollow metal member extending into said chamber through said hole connected to and supporting the cathode at the closed end thereof, an elongated metal screen sealed with respect to said housing and surrounding said elongated hollow member and spaced therefrom to provide a relatively narrow long space between the screen and said elongated member extending from the housing to the inner end of said member, insulating means outside said housing between said member and said screen, and means for introducing a cooling medium into said hollow member.

5. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated metal housing providing a chamber for receiving articles to be coated, an anode supported within said housing and insulated therefrom, said housing having a hole therein, a cathode, a closed end elongated hollow metal member extending into said. chamber through said hole connected to and supporting the cathode at the closed end thereof, an elongated metal screen sealed with respect to said housing and surrounding said elongated hollow member and spaced therefrom to provide a relatively narrow long space between the screen and said elongated member extending from the housing to the inner end of said member, insulating means outside said housing between said member and said screen, and means terminating adjacent the closed end of said elongated member for introducing a cooling medium into said hollow member.

6. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated housing providing a chamber for receiving articles to be coated, an anode supported within the housing and insulated'therefrom, a cathode, said housing having a hole therein, an elongated metal member extending into said chamber through said hole connected to and supporting said cathode at the inner end thereof, a metal screen sealed with respect to said housing surrounding said elongated member so as to provide a relatively long narrow space between the screen and said member extending from the housing to the inner end of said member, insulating means arranged outside said housing between said member and said screen, and a cap secured to said screen spaced from the inner end of said member, and said cap having a perforation therein surrounding the cathode.

7. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated housing providing a chamber for receiving articles to be coated, an anode supported within the housing and insulated therefrom, a cathode, said housing having a hole therein, an elongated metal member extending into said chamber through said hole connected to and supporting said cathode at the inner end thereof, a metal screen sealed with respect to said housing surrounding said elongated member so as to provide a relatively long'narrow space between the screen and said member extending from the housing to the inner ened of said member, insulating means arranged outside said housing between said member and said screen, and a cap carried by said screen having a perforation therein providing communication from said chamber to said space. I

8. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated housing providing a chamber for receiving articles to be coated, an anode supported within the housing and insulated therefrom, a cathode, said housing having a hole therein, an elongated metal member extending into said chamber through said hole connected to and supporting said cathode at the inner end thereof, a hollow metal screen sealed with respect to said housing extending into said chamber through said opening and surrounding said elongated member so as to provide a relatively long narrow space between the screen and said member extending from the housing to the inner end of said member, insulatingmeans arranged outside said housing between said member and said screen, and means for introducing a cooling medium into said hollow screen.

9. Apparatus for coating articles by cathode disintegration comprising in combination, an evacuated housing providing a chamber for receiving articles to be coated, an anode supported within the housing and insulated therefrom, a

cathode, said housing having a hole therein, an elongated metal member extending into said chamber through said hole connected to and supporting said cathode at the inner end thereof, a plurality of concentrically arranged screens extending into .said chamber through said hole and surrounding said member, and insulation means arranged outside said housing between the screens and between said member and an adjacent screen.

- BERNHARD BERGHAUS. WILHELM BURKHARDT. RUDOLF REINECKE. 

